Hydrogenation, a reaction of reducing carbon-carbon double bonds to saturated alkanes in hydrogen atmosphere with the presence of a catalyst, is common in processes of oil refining, food, pharmaceutical manufacturing, and chemical commodity. For example, removing sulfur, nitrogen, nickel or vanadium from oil by hydrogenation; reducing the unsaturated fat in vegetable oil through hydrogenation; adding hydrogen to unsaturated chain segments of copolymers to transform the molecular structures and characteristics such as hydrogenation of benzene rings can reduce UV degradation of aromatic epoxy resins. Hydrogenated alicyclic polycarboxylic acids have been used in functional polyimide or functional epoxy resin hardeners; hydrogenated cyclohexane dicarboxylic acid ester can replace phthalate to serve as a plasticizer in PVC processing or as a coating material, a filling and reinforcing material or a processing agent. For PVC processing, currently, PAE (phthalate ester) series products/derivatives such as dibutyl phthalate (DBP), dioctyl phthalate (DOP) or diisononyl phthalate (DINP) have been widely used as plasticizers. However, such substances, denounced as hazardous substances in recent years, have been prohibited to be used in some child and/or infant products gradually. Therefore, phthalate has been replaced by some alicyclic dicarboxylic acid esters that are regarded as environment-friendly substances in applications of plasticizers. For example, 1, 2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH) is normally produced, as described in the prior art, by saturating the benzene rings of polycarboxylic acids or their derivatives through hydrogenation, which also remove the toxicity of them.
The catalyst used for hydrogenation reaction is a considerable issue. In the prior art, the U.S. Pat. No. 6,284,917B1 discloses that bimodal alumina with macropores is selected as a support for production of supported ruthenium catalyst to produce corresponding alicyclic carboxylic esters using a high pressure batchwise stirred reactor (autoclave) at 80° C. and 100-200 bar.
The Chinese Patent, CN102658182B, discloses that phosphorus-modified alumina (P—Al2O3) can be used as a support and loaded with nickel to give a catalyst which can be used in production of corresponding alicyclic carboxylic esters in a continuous fixed-bed reactor at temperature from 150 to 200° C. and pressure between 30 and 150 bar.
The U.S. Pat. No. 7,595,420B2, discloses a silica material with ordered pores, MCM-41, can be used as a catalyst support for production of supported ruthenium catalysts and used to give corresponding alicyclic carboxylic esters at 120° C. and 58 to 200 bars using a high pressure batchwise stirred reactor (autoclave).
The U.S. Pat. No. 8,722,922B2, discloses a supported catalyst, group VIIIB transition metals such as Pd and Ru loaded on 2A-alumina support (2A-Al2O3), can be used in production of corresponding alicyclic carboxylic esters in a fixed-bed reactor at temperature from 100 to 250° C. and pressure between 1 and 50 bar.
The U.S. Pat. No. 8,586,784B2, discloses a supported catalyst prepared with titanium dioxide (TiO2, as a support) can be used in production of corresponding alicyclic carboxylic esters in a continuous fixed-bed reactor at 100° C. and pressure of 100 bar.
According to the above-mentioned prior art, in most of the inventions, to make the hydrogenation rate of benzene rings reach higher than 90%, the hydrogenation of aromatic polycarboxylic acid esters needs be carried out under the condition of high pressure (>100 bar) or high temperature (higher than 100° C.) or both high pressure and high temperature which leads to the high cost of investment and the high cost of subsequent operation and maintenance.